Process for preparing boiled noodles

ABSTRACT

Combination use of citric or/and lactic acid with table salt in one solution is extremely effective to enhance the preservability of boiled noodle products to be commercially distributed at an ordinary temperature. Boiled noodles are subject to immersion treatment with the aqueous solution containing said combination and then, without rinsing, packaged and heat sterilized for commercial distribution. Additional use of sodium glutamate is proposed for improving palatability if desired.

This application is a continuation of copending U.S. patent applicationSer. No. 523,892, filed Aug. 15, 1983, now U.S. Pat. No. 4,552,772,which, in turn, is a continuation of U.S. patent application Ser. No.312,259, filed Oct. 13, 1981, now abandoned.

This invention relates to a process for preparing noodles and moreparticularly is concerned with a process for preparing packed boilednoodles capable of being commercially distributed at ordinarytemperature.

In preparing so-called boiled noodles, sterilization treatment of theboiled noodles with hydrogen peroxide was deemed in the past to be themost effective temporary measure to enhance the possibility ofcommercial distribution thereof. In view of anxiety for adverse effecton human health, however, there is no alternative but to suspend the useof hydrogen peroxide in present circumstances. As a substitution for theuse of hydrogen peroxide, there has been proposed a process knownphysically as so-called retort treatment. This process, however, has notcommercially established yet, because gumming or coloration of noodlestreated thereby is brought about and, moreover, packing materials andapparatuses necessary therefor unavoidably raise the cost of production.Further, some chemical treatment processes have been proposed for thepurpose, though they have both merits and demerits. For instance, aprocess relying on addition to noodles of alcohol and lower fatty acidesters or on immersion therein of the noodles cannot be put in practicaluse in point of taste with relish, because the use of said alcohol andsaid esters in high concentration is necessary to preserve the treatednoodles for a long period of time, though the process is serviceable tomaintain antibacterial activity of the treated noodles to a considerableextent. Lysozyme treatment is a process which costs dearly and theeffect thereof is not prudential. In view of popularity in character ofthe goods with which the present invention deals, threfore, it isdifficult to put it to practical use. Combination use of organic acidswith fatty acid esters, glycine, alcohol, etc., is actually used to acertain extent this present. In order to assure satisfactory taste ofthe noodles with relish according to the process relying on thecombination use of such additives, however, there is no alternative butto reduce the additives in amount, thereby rendering the treated noodlesdistributable commercially for a period of about one week, or toincrease the additives in amount in order to attain commercialdistribution thereof at ordinary temperature for a long period of time(3 months), sacrificing the taste with relish of the treated noodles.Finally, there is known a process as a special embodiment of theabove-mentioned process wherein noodles are treated with an organic acidto reduce usually in pH up to 5.0 and up to 4.5 in the extreme. Althoughnoodles are improved in their preservability when a pH value thereof isreduced, it is impossible to reduce the pH value to a level of lowerthan 4.5. It is a technical knowledge common to those skilled in the artthat even when the pH value of noodles is reduced by any chance to alevel of lower than 4.5, there is no way of preventing such drawbacksthat because of their strong acid taste, the thus treated noodles willno longer be serviceable for ordinary cooking, will suffer from severeroughness when they are boiled, will be too soft, and they will mutuallyadhere to one another or conspicuously suffer from roughness when theyare fried in a hot pan.

Extensive researches prosecuted by the present inventors on theabove-mentiond subject have resulted in the finding that, contrary tothe prior art general concept, boiled noodles can be prevented from rotover such long period of 6 months or so at a temperature of about 37° C.while avoiding deterioration in taste of the boiled noodles by the useof a specific organic acid in an amount sufficient to reduce a pH valueof the boiled noodles to a level lower than 4.3 and table salt and, ifnecessary, allowing sodium glutamate to coexist therewith.

In accordance with the present invention, there is provided a processfor preparing wheat flour-based noodles capable of being commerciallydistributed at ordinary temperature and of being ready for cooking in amoment, characterized in that wheat flour-based noodles shaped intodesired form are boiled, water-washed and then subjected to immersiontreatment in an aquenous solution containing (a) citric acid or lacticacid or mixtures thereof and (b) table salt and, if necessary, (c)sodium glutamate, followed by packaging and heat sterilization.

The process according to the present invention is fundamentallydifferent from the prior art process wherein citric acid and/or lacticacid, table salt, sodium glutamate, etc. are mixed with starting wheatflour at the time of preparing noodles (where a dough is formed byadding water to the starting wheat flour) in that in the present processthe shaped noodles are boiled and then immersed for a short time in anaqueous solution containing citric acid and/or lactic acid, table saltand sodium glutamate. If the ingredients which are to be present in thetreatment solution according to the present invention are incorporatedfrom the beginning into a dough at the time of preparing noodles, anelution loss of the ingredients into the boiling water during theboiling step of the noodles becomes large, with the result that not onlythe quantitative control of the ingredients which are to be adherent tothe end product noodles inherently becomes difficult but also the use ofsuch large amounts of the ingredients as may adversely affect the noodlequality sometimes happens. As mentioned previously, the incorporation ofthe organic acid into the dough at the time of preparing noodlesterribly deteriorates the noodle quality.

In practicing the present invention, boiled noodles are immersed for30-60 seconds, preferably 45-60 seconds, in an aqueous solution whichhas previously been prepared in such a manner that a concentration inthe solution of citric acid and/or lactic acid is 1.0-0.4%, preferably0.8-0.5%, that of table salt is 0.8-0.2%, preferably 0.6-0.3% and, ifnecessary, that of sodium glutamate is 0.09-0.02%, preferably0.06-0.04%, and the temperature of the solution is kept at ordinarytemperature up to 50° C., preferably 30°-40° C. Thereafter, the noodlesthus treated are put into a package and the package is sealed, followedby sterilization using such heating means as hot vapor or water. Theboiled noodles thus obtained have a pH of 3.9-4.3 as measured accordingto the pH measuring method (10 g of the noodles charged with 50 ml ofdistilled water are homogenized and allowed to stand for 30 minutes andthen measured for pH with an electrode type pH meter) commonly adoptedin this technical field. Further, the amount of table salt adherent tothe noodles is 0.05-0.15% and that of sodium glutamate, when used ifany, is 0.01-0.02%.

The process of the present invention is applicable to boiled noodles outof wheat flour-based noodles. The expression, "boiled noodles", used inthe specification is to mean that the noodles have already been treatedin boiling water so that such noodles are ready for quick cooking. Theterm, "table salt", as used herein means sodium chloride. Further, theterm, "noodles" or "pastas", as used herein should be understood in thebroadest sense to cover not only typical Japanese style noodles mainlycomposed of wheat flour added with or without eggs or yolks, but alsoany kinds of pastas including macaroni, spaghetti and vermicelli. Theexpression, "wheat flour-based", as used herein is to mean that theproduct concerned is mainly composed of wheat flour of any typeincluding semolina, and said expression does not intend to exclude theinclusion of any other additives into the wheat flour.

By utilizing the present invention for the preparation of boiled noodlesof the above-mentioned types, it is possible to commercially distributesaid boiled noodles at ordinary temperature with substantial safety overa long period of 6 months, whereby no hindrance is brought about to thetaste inherent in boiled noodles and no particular increase in theproduction cost is entailed. In accordance with the present invention,there has been found that, contrary to the prior art common concept, thesolution treatment according to the present process is successful inreducing a pH value of boiled noodles to a level lower than about3.9-4.3 and thereby to attain an unexpected possibility of commercialdistribution of the boiled noodle products at ordinary temperature for along period of time and, at the same time, that the deterioration intaste of the boiled noodle products inherent to the lower pH valuethereof can be covered up by the coexistence therewith of table salt.

Boiled noodles which are to be treated according to the process of thepresent invention are prepared in the manner known to those skilled inthe art. That is, starting materials for making noodles, such as wheatflour or the like, are charged with appropriate amounts of water andthen kneaded, and the kneaded product, in case it is wheat flour noodlesof the Japanese style, is rolled and shaped into a desired form by meansof cutting blade. In the case of macaroni, spaghetti, etc., the kneadeddough is extruded,. as it is, into a desired form by means of highpressure extrusion technique. The noodles shaped into a desired form inthe above manner are boiled and then water-washed to prepare so-calledboiled noodles.

In order to facilitate further the understanding of characteristicfeatures of the process of the present invention, each feature isexplained hereinafter with reference to data obtained therefor.

First, in the present process, it is essential to use citric acid orlactic acid, particularly both of them. From the standpoint ofpreservability, it is necessary that the boiled noodles according to thepresent invention should have a pH value of 3.9-4.3. Although such pHvalue, per se, can be attained by the use of various organic acids, ithas now been found that among such usable organic acids the use ofcitric acid or lactic acid, particularly combination use of citric acidand lactic acid, is suitable for attaining the desired pH value. Theselection of citric acid or lactic acid or both of them is decideddepending on their inherent tastes such as sourness, astringency andbitterness. Then, illustrated below is the taste of boiled noodles whenthey are treated respectively with various organic acids in accordancewith the process of the present invention.

    ______________________________________                                                                    Practical                                         Organic acid                                                                            Taste             usefulness                                        ______________________________________                                        Malic acid                                                                              Refreshing sourness but                                                                         Poor                                                        stimulative                                                         Tartaric acid                                                                           Strong sourness and                                                                             Poor                                                        astringency                                                         Gluconic acid                                                                           Mild sourness but bitter-                                                                       Poor                                                        ness as aftertaste                                                  Citric acid                                                                             Mild and refreshing sour-                                                                       Good                                                        ness and weakly stimulative                                                   (feels somewhat cool)                                               Lactic acid                                                                             Non-direct, mild and weak                                                                       Good                                                        sourness but somewhat                                                         bitter                                                              Citric acid/                                                                            Considerably weak sourness,                                                                     Particularly                                      lactic acid                                                                             when compared with indi-                                                                        good                                                        vidual acids used singly,                                                     without astringency, etc.                                           ______________________________________                                    

The following are the results of investigation conducted to obtain therelationship between pH and preservability of boiled noodles whentreated with citric acid.

    ______________________________________                                        Number of bacteria                                                            on noodles before                                                                         pH of noodles                                                     boiling     4.1   4.2   4.3  4.4   4.5    4.6                                 ______________________________________                                        10.sup.4 -10.sup.5 /g                                                                     0     0     0-2  51-74 204-313                                                                              400-530                                                     (0.6)                                                                              (62)  (251)  (463)                               10.sup.2 -10.sup.3 /g                                                                     0     0     0    21-33 108-256                                                                              350-466                                                          (22)  (174)  (401)                               ______________________________________                                    

The above data showing the minimal and maximal values of the number ofspoiled boiled noodles were obtained in the tests mentioned above,wherein 5 lots, each consisting of 2000 packages of boiled noodles to beinspected, were stored at 37° C. for 6 months, while the parenthesizedare such values as averaged.

From the data shown above, it is understood that critically important isto adjust a pH of boiled noodles to below 4.3 from the standpoint ofpreservability of the noodles. With the view of lightening sourness ofsuch boiled noodle products, the present inventors prosecuted researchesand have eventually realized that the palatable taste of boiled noodlesis markedly improved by the use of table salt in combination with sodiumglutamate according to circumstances. In obtaining boiled noodles of pH4.1 by the use of an aqueous citric acid solution while adding theretovarying amounts of table salt and sodium glutamate, organoleptic testresults obtained as to the sourness, salty taste and taste of sodiumglutamate of the resultant boiled noodle products were as in thefollowing.

    ______________________________________                                        Amounts of table salt                                                         and sodium glutamate                                                                         Organoleptic test results of                                   adhered to noodles                                                                           boiled noodle product (pH 4.1)                                          Sodium              Salty                                                                              Taste of sodium                             Table salt                                                                             glutamate Sourness  taste                                                                              glutamate                                   ______________________________________                                        <0.05%   --        +         -    -                                           0.05-0.15%                                                                             --        -         -    -                                           >0.15%   --        -         +    -                                           --       <0.01%    +         -    -                                           --       0.01-0.02%                                                                              -         -    +                                           --       >0.02%    -         -    +                                           0.05-0.15%                                                                             0.01-0.02%                                                                              -         -    -                                           ______________________________________                                    

It is understood from the above data that the taste of boiled noodlesthus treated can perfectly be normalized palatably by virtue of allowing0.05-0.15% of table salt (0.01-0.02% of sodium glutamate may be allowedto coexist therewith if desired) to adhere to the boiled noodles.

There has been no such precedent heretofore, wherein even for anypurposes table salt was mixed, or allowed to adhere to, in boiled noodleproducts, such as spaghetti or macaroni. In the case of boiled wheatflour noodles of Japanese style (boiled noodles in a narrow sense),table salt is often added, together with water, to wheat flour in thestage of making noodles (dough formation), however, the purpose of theaddition of table salt is not at all to improve palatable taste of thenoodles but is to tighten noodle dough while promoting gluten formationor prevent said noodle dough from attaching to a noodle-making machine.In the use of table salt according to the prior art, the salt is usuallydissolved in water which is to be added to wheat flour in the initialstep of noodle-making process, and the amount of the salt added isconsiderably large, e.g. 2-3% based on raw noodle (5-8% in the case ofhandmade noodle) and considerable portion of the salt remains in theboiled noodles even when the salt has flowed by elution into boilingwater. However, the amount of table salt used in the process of thepresent invention is such very small as less than 0.15%, and the purposeof using the salt is to lighten sourness and improve physical propertiesof the boiled noodles (prevention of excessive softening noodle and ofrough appearance when a pH thereof is lowered), and thus the use oftable salt according to the present process is different in its purposesfrom the prior art use of table salt in noodle-making. Furthermore, thepresent process is applicable to boiled wheat flour noodles afterJapanese style which have been made while incorporating table salt intonoodle dough at the time of preparation thereof, but it should beconstrued that the presence of table salt incorporated into the noodledough is not an essential requisite in the present process. Recenteating habits tend rather to reduce the salt content in foods as loweras possible, and under such circumstances the present process may besaid to possess a prominent advantage, wherein perfect improvement inpalatable taste of boiled noodles can be realized by simply providingthe boiled noodles with small amounts of table salt which is allowed toadhere to therein.

It is to be understood that during immersion treatment with boilingwater, the α-conversion of wheat flour starch is achieved up to 50-70%,and some marginal conversion is expected at the stage of heatsterilization. Because of this, the boiled noodle product obtained fromthe present invention is very quickly brought up to an edible state.

Examples of the present invention are given below in order to illustratethe invention more concretely, but is should be construed that theexamples are in no sense limitative.

EXAMPLE 1

Boiled noodles of the Japanese style were made according to the usualway in a noodle-making line capable of making 30 packages per minute,each package containing 200 g of boiled noodles as one meal portion, byprocessing 6 bags of wheat flour (each bag containing 25 kg) per hour.In a 350 l vessel, 2.4 kg of citric acid, 1.2 kg of table salt and 150 gof sodium glutamate were dissolved in water to make 300 l of aprocessing solution. In this processing solution were immersed boilednoodles for 45 seconds, followed by draining. The boiled noodles thustreated were packaged and subjected to boiling water treatment at 95° C.for 30 minutes. This packaged boiled noodles had a pH of 4.1, and 0.1%of table salt and 0.01% of sodium glutamate, both having adhered to thenoodles.

The processing solution thus used is kept at 30° C. and charged dropwisewith 20 ml per minute of a 50% aqueous citric acid solution and 35 mleach of a 20% table salt water and of a 2% aqueous sodium glutamatesolution so that the processing solution maintain its initialconcentration.

2000 Packages of boiled noodles thus treated were stored at 37° C. for 6months, whereupon no spoiled product was found and both noodle qualityand palatable taste thereof were found excellent.

EXAMPLE 2

The same treatment as in Example 1 was repeated, except that a 1:2mixture of 800 g of citric acid and 1600 g of lactic acid was used inplace of the citric acid used singly. The thus treated boiled noodles aspackaged had a pH 4.0 and exhibited preservative effect similar to thatshown in Example 1, retaining favorable noodle quality and the palatabletaste of the boiled noodles were more superior over that of the boilednoodles obtained in Example 1.

EXAMPLE 3

The same treatment as in Example 2 was repeated, except that a mixture(2:1 mixture) of 1600 g of citric acid and 800 g of lactic acid wasused. The packaged boiled noodles thus treated had a pH of 4.1 andshowed preservative effect, noodle quality and palatable taste allsimilar to those of the boiled noodles obtained in Example 2.

EXAMPLE 4

To 5 kg of wheat flour was added 1.4 l of water and the mixture wasprocessed with a mixer, extruder and roller to prepare a dough which wasthen shaped into a spaghetti-form by the use of circular No. 14 cuttingblades (φ=1.9 mm). The noodles thus obtained were boiled for 9 minutesto obtain about 12.5 kg of boiled noodles.

The boiled spaghetti thus obtained was then immersed into 70 l of aprocessing solution in which 560 g of citric acid and 210 g of tablesalt were contained. The thus immersed spaghetti was drained and thenplaced in packages each containing about 200 g of the boiled spaghetti.The packaged boiled spaghetti was then heat-treated at 95° C. for 30minutes with a steam kettle. This packaged boiled spaghetti had a pH of3.95 and 0.10% of table salt adhered thereto.

50 Packages of the thus treated boiled spaghetti were stored at 37° C.for 6 months, whereupon no spoiled product was found and both spaghettiquality and palatable taste were found excellent.

EXAMPLE 5

There was prepared 70 l of a processing solution wherein 490 g of citricacid and 350 g of table salt were dissolved. The boiled spaghettiprepared in Example 4 was immersed for 45 seconds in the processingsolution kept at 35° C. After draining, 200 g each of the thus treatedboiled spaghetti were placed in packages and then heat-treated at 95° C.for 30 minutes, followed by cooling with water.

The thus treated packaged boiled spaghetti had a pH of 4.25 and tablesalt in an amount of 0.14% adhered to the boiled spaghetti.

EXAMPLE 6

A mixture comprising 25 kg of wheat flour, 7.0 l of water and 375 g oftable salt was shaped into spaghetti of about 1.9 mm in diameter bymeans of a macaroni extruder. This spaghetti was boiled for 7 minutes toobtain boiled spaghetti which was then immersed for 45 seconds into asolution prepared by dissolving 800 g of citric acid and 60 g of sodiumglutamate in 100 l of water and kept at 30° C. The boiled spaghetti wasthen placed into 330 packages each containing 200 g of the boiledspaghetti and steam heated at 95° C. for 30 minutes to obtain packagedboiled spaghetti.

The boiled spaghetti as packaged had a pH of 4.1, 0.12% of table saltand 0.01% of sodium glutamate, both adhered to the boiled spaghetti.

EXAMPLE 7

A mixture comprising 25 kg of wheat flour and 7.0 l of water was shapedinto a spaghetti form of 1.9 mm in diameter by means of a macaroniextruder. The spaghetti thus obtained were boiled for 7 minutes toobtain boiled spaghetti. The boiled spaghetti was immersed 45 secondsinto a solution prepared by dissolving 800 g of citric acid, 400 g oftable salt and 60 g of sodium glutamate in 100 l of water and keepingthe solution at 30° C. The boiled spaghetti was then put into 330packages each containing 200 g of the boiled spaghetti and thensteam-heated at 95° C. for 30 minutes to obtain the packaged boiledspaghetti.

The packaged boiled spaghetti had a pH of 4.1, and 0.13% of table saltand 0.01% of sodium glutamate, both having adhered to the boiledspaghetti.

EXAMPLE 8

Boiled spaghetti was obtained according to the procedure of Example 7,and the boiled spaghetti was then immersed for 45 seconds into asolution prepared by dissolving 460 g of citric acid, 230 g of lacticacid and 250 g of table salt in 100 l of water and keeping at 30° C. Theboiled spaghetti thus treated were packaged and steam-heated in the samemanner as in Example 7 to obtain packaged boiled spaghetti.

The boiled spaghetti thus obtained had a pH of 4.3, and 0.05% of tablesalt having adhered to the boiled spaghetti.

EXAMPLE 9

The boiled spaghetti obtained according to the procedure of Example 4was immersed for 60 seconds in 30 l of water kept at 40° C. in which 75g of citric acid, 150 g of lactic acid, 105 g of table salt and 27 g ofsodium glutamate were dissolved. Thereafter, the same procedure as inExample 4 was repeated to obtain packaged boiled spaghetti. The boiledspaghetti thus obtained had a pH of 4.0, and 0.12% of table salt and0.02% of sodium glutamate, both having adhered to the boiled spaghetti.

EXAMPLE 10

A mixture comprising 10 kg of wheat flour and 3.0 l of water was shapedinto a dough sheet by means of a press roll and the dough sheet was cutwith a square cutting blade No. 10 into raw Japanese noodles(cross-section of about 2 mm×3 mm). The raw Japanese noodles were boiledfor 20 minutes to obtain about 28 kg of boiled noodles. The boilednoodles thus obtained were immersed for 45 seconds into a solutionprepared by dissolving 400 g of citric acid and 200 g of table salt in50 l of water and keeping at 30° C. The boiled noodles thus treated wereplaced into packages each containing 200 g of the boiled noodles,followed by steam-heating at 95° C. for 30 minutes to obtain packagedboiled noodles. The packaged boiled noodles had a pH of 4.1, and 0.11%of table salt having adhered to the boiled noodles.

EXAMPLE 11

Boiled Japanese noodles were obtained by repeating the operation ofExample 10 except that 10 kg of wheat flour was kneaded together with100 g of table salt and 3.0 l of water. The boiled noodles thus obtainedwere immersed for 45 seconds in 50 l of water in which 400 g of citricacid and 100 g of table salt were dissolved. The boiled noodles thustreated had a pH of 4.1, and 0.15% of table salt having adhered thereto.

What we claim is:
 1. Cooked wheat-flour based pastas ready for rapidcooking prepared by boiling said pastas and washing said boiled pastaswith water, the improvement which comprises immersing the boiled pastasin an aqueous solution containing (a) at least one of citric acid andlactic acid and (b) table salt, then packaging and heat sterilizing thepastas which have been immersed, said aqueous solution having a pH suchthat the pH of the boiled pastas, after immersion, is about 3.9 to about4.3.
 2. The pastas of claim 1 which are selected from the groupconsisting of macroni, spaghetti, vermicelli and Japanese style noodles.3. The pastas of claim 1 which are Japanese style noodle pricipallycomprised of wheat flour and whole eggs or egg yolks.